Control for fuel supplies



Patented Apia l3, i943 CQN'I'ROL FOR FUEL SUPPLIES Stanley M. Udale,Detroit, when, assignorto George M. Holley and Earl Holley ApplicationAugust 23, 1940, Serial No. 353,782

3 Claims.

The object of this invention is to control the rate of fuel flow toeither a carburetor or to a fuel injection system by means of the airflow through a venturi and the flow of the fuel through a fuel venturi.

In the drawing, the figure shows diagrammatically the application of thedevice to a carburetor.

In the figure, 1B is the air entrance controlled by two valves ii and itconnected by linkage is. which valves in the position shown permit warmair to enter the air entrance l8. Associated with the air venturi M isan annular chamber i 5 communicating through the opening it with thethroat of the venturi i l. 3? is the correspondlng fuel venturi whichderives its fuel from the fuel pipe iii, the fuel flowing to the chamberl9 and down past the needle 213 through a passage 25 to the fuel outlet22, which fuel outlet is controlled by a needle 23, which needle iscontrolled. by a bell crank lever 2 3 mounted on the pin '25. The needle25 is connected through this bell crank lever with the rod ill and iskept in engagement by means of the compressed spring 26 which isadjusted by the threaded screw 27. The rod 28 carries an enlargement 352located in the throat of the venturi ill The diaphragm 28 is responsiveto the fuel pressure in the chamher it). The chamber 29 above thediaphragm 28 is therefore at the pressure existing in the throat of thefuel venturi ll, for the reason that the passage Jill connects thethroat of the venturi ll with the chamber A rod 3i connects thediaphragm 28 and the rod at with another diaphragm 3?. which forms theupper wall of a chamber 33.

The pin 3i slides through an opening in the Wall 35 which forms thepartition between the chamber l gand the chamber 33. A small quan tityof fuel therefore leaks past the pin' 3! into the chamber 33 and sofinds its way to the annular chamber it and so to the passage 35, whereit discharges through the openings 38 and 37. A chamber 39 is locatedabove the diaphragm 32 and is connected through a passage all withtheannular chamber 9 and so with the openings ill in the outlet from theventuri M. An aneroid barometer 12 operates through a lever 43 with avalve 44 which at high altitude permits a flow of air from the chamber39 to the chamber 33 This is the Well known altitude correction tocorrect for the changes of density in the air.

In order that the delay inevitable between the opening of the-throttle38 and the opening of the needle valve 23 does not disturb the mixtureof the delay above referred to.

Operation Assuming that the engine connected to this particularcarburetor is already running, then the throttle 38 causes a suction atthe outlet 3? located near the downstream lip of the throttle so as tocause air flow from the opening 36, causing the idle fuel to be drawndown the-passage from the annular chamber l5 and so from the chamberThis causes a slight suction in the chamber 33 which increases as thethrottle opens. Later when the throttle opens beyond the range of 35,ill, the suction in the throat of the venturi id increases still moreand the diaphragln descends compressing the spring '25 and opening theneedle 23. thereby causing'an increase in the fuel flow through theventuri ll.

which causes the diaphragm 28 to rise because I of the suction in thechamber 29. A balance is thus reached in which the mixture ratio isdeterruined by the relative area of the. throats of the venturis ll andi i and therefore by the diameter of the rod 233 at the throat and theenlargement M32 is located here.

It is desirable at extremely low fuel flows and at extremely high fuelflows that the mixture ratio should be rich, richer by say 50%, than thecruising lean mixture ratio. To attain this result the rod at has adefinite contour as, indicated by the enlargement 32. When the throat ofthe venturi ll is small a relatively small fuel flow will cause a greatsuction in the chamber 29 and therefore will balance a relatively greatair flow through the venturi i4. In other words, a lean mixture willresult. When the throat of the fuel venturi ll is large a relativelylarge flow through the venturi i! is required to balance a relativelysmaller flow through the venturi it. In other words, a rich mixtureresults. Although it is not absolutely necessary a bumper spring M isprovided above the diaphragm 32. The enlargement I02 in the rod 20 thuscontrols the trance a streamlined obstruction located in the throat ofsaid fuel venturi, aventuri in said en-' trance, an outlet from saidfuel venturi a valve located some distance away from said venturi insaid outlet from said fuel venturi, a diaphragm responsive to thepressure difference created by the fuel venturi, a second diaphragmresponsive to the pressure difference created by the air venturi, manualmeans for controlling the air throttle, means for rigidly connecting thetwo diaphragms together, said diaphragms being adapted to'be inequilibrium when subjected to the fuel and air pressures correspondingto the normal fuel and air flows, said connecting means being alsoconnected to the fuel throttle valve and to the streamlined obstructionlocated in the a second diaphragmresponsive on one side to the auctionin the throat of the air venturi, and on the other side to the normalpressure in the air e, means for rigidly. connecting the two diaphragmstogether, said diaphragms bein adapted to be in equilibrium whensubjected to the fuel and air pressures corresponding to the normal fueland air flowsJaid connecting means being also connected to the fuelthrottle valve 10 and to the streamlined obstruction located in thethroat of the said fuel venturi so as to form therev with anautomatically variable throat and in which the maximum diameter of theobstruction is located at theminimum diameter of the venturi at a fuelflow intermediate the maximum and 0 through said venturi, said valveconstituting the throat of the said fuel venturi so asto form therewithan automatically variable throat and ,a fuel entrance, 9. fuel passageconducting fuel to said engine, a fuel venturi therein, a streamlinedobstruction located'in the thmat of said fuel venturi; an outlet orificelocated in said fuel only movable obstruction in the air passage, a fuelentrance, a fuel venturi therein, an outlet from said venturi, astreamlined obstruction located in the throat of said venturi, a fuelthrottle valve located some distance away from said venturi in saidoutlet from said venturi, a diaphragm responsive to the pressure drop inthe throat of the fuel venturi, a second diaphragm responsive to thedrop in the throat of the air venturi, means for rigidly connecting thetwo diaphragms topassage adapted to discharge fuel into said airpassage, a fuel throttle valve regulating the size ofsaid orifice, adiaphragm responsive on one side to the fuel pressure and on the otherside to the pressure in the throat of said fuel venturi,

gether, said diaphragms being adapted to be in equilibrium whensubjected to the fuel and air pressures corresponding to the'normal fueland air flows, said connecting means being also connected'to the fuel'throttle valve and to the streamlined obstruction located in the throatof said fuel venturi for moving said obstruction relative to saidventuri for the purpose of varying the effective throat diameter of saidfuel venturi.

STANLEY M. UDALE.

